On Jan. 13, California health officials issued a hold on 330,000 doses of Moderna’s COVID-19 vaccine after “fewer than 10” people at San Diego’s Petco Park stadium vaccine clinic suffered allergic reactions to the vaccine. Santa Clara County officials lifted the hold on the vaccine lot in question on Jan. 21.
One day later, on Jan. 22, the Centers for Disease Control and Prevention (CDC) issued a Morbidity Mortality Weekly “early release” report on Moderna’s COVID-19 vaccine. For the report, the CDC used data reported to the Vaccine Adverse Event Reporting System (VAERS) between Dec. 21, 2020 – Jan. 10, 2021 to investigate cases of anaphylaxis, a life-threatening allergic reaction, following injections of Moderna’s vaccine.
The CDC’s choice to use VAERS data to calculate the rate of anaphylaxis associated with Moderna’s vaccine is idiosyncratic and troubling. Why?